Hand held, manually powered carts for transporting an auxiliary power supply are known in the prior art. While the prior art devices are capable of carrying and transporting an auxiliary power supply such as a battery, their design has limited their usefulness in some applications. One of the problems with the present cart devices is their unsuitability for carrying liquid-containing batteries, such as the common lead-acid batteries, in a level position. Tilting such batteries can result in spillage of the corrosive acid contents of the batteries, potentially making them inoperable or less effective as auxiliary power supplies. Additionally, spillage of the corrosive acid results in environmental pollution, can affect ground water supplies, and may cause harm to the epidermis or clothing of any individual coming in contact with it. If the user must strain to maintain the cart in a position in which the battery remains level, the maneuverability and ease of use of the cart becomes limited. A portable battery power source that solves these problems would provide a decided advantage over the prior art.